We propose to study, using techniques of somatic cell genetics, (1) human genetics and (2) virus-cell interaction. We will develop and use a number of selective systems involving purine and pyrimidine pathways for the chromosomal assignment and regional mapping of human genes. Clone panels of human-rodent hybrids will be constructed for the purpose of mapping unselected genes. Furthermore, we will explore gene transfer techniques using herpes simplex viral DNA as the mediator, with the hope that these methods can be used for the transfer of cellular genes from one cell type to another.